Dozing operation by the use of a bulldozer has been previously performed in such a manner that: the operator who drives a bulldozer manually operates a blade to be lifted or lowered so as to keep loads applied to the blade by excavating and moving earth constant while eliminating running slip of a vehicle body (i.e., shoe slip) for the sake of efficiency on dozing operation and so as to level the ground with the position of a cutting edge of the blade being kept constant with respect to the ground.
However, the above-described manual operation for lifting or lowering a blade so as to keep loads on tile blade constant while eliminating shoe slip for the sake of efficiency on dozing operation and so as to level the ground with the position of a cutting edge of the blade being kept constant with respect to the ground presents the following disadvantages. Even if the operator is very skillful, he has to carry out lifting/lowering operation a number of times so that he will get significantly exhausted. Another disadvantage is that because the operation is very complicated, the unskilled operators, as a matter of course, will be significantly exhausted with fatigue, and the operation itself will be found as quite difficult to be carried out.
The prime object of the invention is therefore to provide a dozing system for a bulldozer with which dozing can be easily carried out by a simple operation, without causing a great deal of fatigue to the operator so that the foregoing problems can be overcome.